The invention relates to a filter device for separating water and other impurities from liquid fuels with a housing body having a first filter element disposed in its interior and a water collecting vessel disposed underneath the filter element.
DE 33 06 294 C2 discloses a filter device, which is used to separate water and other impurities from liquid fuels, particularly to separate water and solid particles contained in diesel fuels. The known filter device comprises a housing body in the interior of which a first and a second filter element are arranged. A collector basin is disposed underneath these filter elements. This collector basin has two separate areas for collecting and discharging the impurities and the water. At the lower end, the system is provided with a drain plug. As soon as the removed water has reached a certain amount, the drain plug must be manually opened and the water discharged from the filter device. This is time-consuming; moreover, manual removal of the water is reliable only if an operator checks the entire device at regular intervals.
The object of the invention is to avoid the aforementioned disadvantages and to provide a filter device for separating water and other impurities from liquid fuels, which provides reliably purified fuel without requiring manual maintenance.
This object is attained by the invention as described and claimed hereinafter.
The substantial advantage of the invention is that an automatic water discharge mechanism is provided in the filter device. This ensures nearly maintenance free operation. Only replacing the filter element requires manual intervention in the system.
According to one embodiment of the invention, the pump works in suction operation or pressure operation, i.e., for suction operation it is disposed in the water discharge line. For pressure operation it is disposed in the fuel intake line and thus generates a positive pressure in the filter device, which is relieved by opening a valve in the water discharge line. The water flows out due to the positive pressure within the filter device.
To prevent problems at extremely low temperatures, the filter device is provided with a heating element. This can be a heat exchanger which is supplied with a heat transfer medium. It is also possible to arrange an electrical heating unit in the system, which is actuated when the temperature falls below a certain level. Instead of a heating element, the fuel return flow may be used to heat the fuel. Due to the heat of the engine, the return flow typically has a higher temperature than the fuel coming from the tank. This heated fuel may be supplied to the filter device via a thermostat valve.
The filter device can comprise two filter systems. The first filter is a prefilter, the second a downstream main filter. The two filter systems can be constructed identically and be linked by corresponding adapter elements.
To monitor the performance of the filters, it is possible in accordance with a further embodiment of the invention to utilize pressure sensors. A pressure sensor can measure, for instance, the differential pressure between intake line and discharge line and signal that the filter needs maintenance when the differential pressure exceeds a certain threshold value. If the fuel is supplied to the filter device at a defined pressure, a sensor is required only in the discharge line. Based on the measurement signal of the sensor, a pressure difference caused by the filter device can be determined and displayed.
If the fuel system has been emptied, the system has to be refilled with a corresponding pump. This pump can for instance be a manually operated pump for venting.
Typically, the filter devices according to the invention are used in trucks, construction machines and the like. To prevent the transfer of vibrations and shocks of the machine to the filter system, a further embodiment of the invention provides for vibration decoupling and arrangement of the filter device on a support structure with corresponding decoupling elements.
These and other features of further preferred embodiments of the invention are set forth in the claims as well as in the description and the drawings. The individual features may be implemented either alone or in combination in the embodiment of the invention or in other fields of application and may represent advantageous embodiments that are protectable per se, for which protection is hereby claimed.